Motor controller



Sept. 27,1927. 43,292

D. H. CHASON MOTOR CONTROLLER Filed Nov. 19. 1924 INVENTOR WIT E555 v fl ATTORNEY Paamted Sept. 27, 1927.

UNITED STATES.

AT NT OFFICE.

DANIEL a. cnason, or ELIZABETH, new masnm-assmimn To run smear. MANU- r'ncrunnte conrm, or ELIZAB TH; new. masnv. a conronaqrron or new nnsnY.

mm conrnounn Application and Iovember 1a, 1024. Serial No. 750,134.

This invention relates to motor-controllers, more particularly of the aphlte disk resistor type,'and has for an o ect to pro- Y vide such a controller with a simplifiedv opcrating mechanism which is particularly adapted for knee-shift operation. Graphite disk rheostats are commonly constructed with a porcelain casing formed with a P811 of wells .each of which is filled w th a stack of the resistor elements or Terminal screws in electrical contact with the end resistor elements are provided at one end of the porcelain casing, and a (yielding bridging1 contact member is arrange at the other en of the casing to beoperated by some pressure exerting means such as an endwise movable rod passin through the casing; Movement of the rod causes the bridgin contact member to firstengage and gradu 1y compress the resistor elements and thereby de--.

crease their electricalresistance. The pressure exerting means has, in practice, only a' limited motion and requires a rather stifi force or pull to operate it, particularly in the latter "stages of its resistor compressing -mo-' tion. Considerable difiiculty has been experienced in devising a satisfactory. linkage of the requisite simplicity and compactness f or operating such a rheostat in connection with 36 for the control of the sewing machine motor.

In accordance with the 'present improve- 'ment, in it's-preferred embodiment, a' bellcrank-lever is fulcrumed on therheostat' su'pport and has one or its arms, which extends transversely of the rheost-at operating rod, aperturedto receive the free end oi such rod on which-is screwed a head. and lock-nut. T An oscillatory shaft adapted to. carry a knee; shift lever is journaled m a bearing boss on the 'rheostat support in endto-end relation, but not necessarily in alinement with the rheostat operating rod. This rock-shaft is connected to rock the bellcrank-lev'er, preferj ably b having fixed to its inner end an arm form with acammedor inclined extremity which-is. engaged by the other arm of the bell-crank lever. A rocking movement of the operating shaft swings the bellcrank- 5 lever andfim arts the desired endwise movement to the r eostat operating rod.

Inthe accompanying drawings," l is a plan view of a sewing machine 'motor con-- "troller embodying the invention. Fig. 2 is a portable and cabinet sewing machineoutfits I.

exert gradually reasing pressures. upon longitudinal vertical section" through the device. Fig. 3 is an endelevation, partly in section. Fig. 4 is a transverse section on the line 4-4, Fig. 1,-and Fig.5 is a perspective view of one of the operating elements of the controller-operating mechanism.

According to the preferred embodiments .of the invention, as illustrated, 1 represents a supporting base for the. rheostat -2 of the well known compression type. Such a rheostat commonly comprises-a. porcelain .body

formed with a pair of wells 3 which are substantiall filled with stacks 4 of resistor "disks 4"and aterminal pressure head 7 is provided at the opposite end of each of such disks of car n, graphite or the like. A terstacks. Slidably mounted in the porcelain body is the. rheostat operatin rod 8, the headed end 9 of which carries t e insulating ushing 10 which is surrounded by the ring 11. vThe rod 8 and; bushing 10 pass S t rough the resilient bridging member 12 and the stifier'backing member 13. Endwise movement of the rod 8 first carries the brldglng member 12 into engagement with the terminal members 7, thus completing the circuit through the rheostat. Further movementof the rod 8 causes the member 12 to the stacks of resistor disks 4, thereby decreasing the electrical resistance of the rheostat. The spring 11 shifts the members 12,

rod 8 is threadedinto an inverted T-shaped guideblock 14, -Figs,'1 and 4, of insulating matenahthe horizontal arms of which slide in ways 15 in the porcelain body and hold. :the rod 8 a ainst twisting; a lock-nut- .16 .bej ing screwe tightly against the guide-block 14. Terminal elements 16, 17 constituting a short-circuiting switch, are connected respectively to the terminal members 5 and tare so arranged that the vertical arm 18 of the guide-block will press the terminal ele-" ment 16 into; contact with the terminal ele- 7 ment 17 and'izshort circuit the rheostat when the resistor disks. are fully compressed.

Such a'rheostat may besec'ured to the. base lby screws19 with its operating rod 8 in end-to-end relation with the rock'shait 20 journaled i'n'the boss 21 formed on-the end p wall 22 risin from the base 1. The rockshaft 20 has ed thereon the collar 23 having a tooth 24 adapted to be engaged by the tooth 25 in the tubular hub end 26 of the knee-shift lever 27 a knee-operated rheostat of this general-character being disclosed, for example, in the U. S. patent to Hemleb, No. 1,444,917, of February 13, 1923.

The inner squared end 28 of the shaft 20 is fixed in a square hole in the operating arm 29, one end of which is referably inclined at so as to be eccentric to the shaft 20 and constitute a cam-ed The arm 29 is formed beyond the cam-edge 30 with a down-turned extremity 31 which is yieldingly held in engagement with the stop 32 on. the base 1 by means of the spring 29* which is connected at its upper end to the lateral projection 29 on the arm 29 and at its lower end is connected to the hook 29 secured to the base 1. The other end 31 of the operating arm 29 is adapted to engage the'stop 32 on the base 1.

Fulcrumed on the screw post 34 fixed to the base 1 is a bellcrank-lever which may be made out of sheet-metal cut and bent to provide the cam-follower or power-arm 35, work-arm 36 and fulcrum-ears 37 through the apertures 38 of which the post 34 passes. The power-arm 35 of the bellcrank-lever is preferably curved transversely of its length, as shown in Figs. 3 and 5; to form a rounded cam-engaging face 39. The workarm 36 of the bellcrank-lever is longitudinally slotted at 40 to freely receive the rheostat operating rod 8 looselysurrounding which is a dished washer 41 which is engaged by the locked nuts 42 on the threaded extremity of the rod 8. I v

It will be readily understood that a limited turning movement imparted to the shaft 20 by the knee-shift lever 27 will, through the cam and bellcrank-lever mechanism, be converted into an efl'ective pull exerted endwise of the resistor compres'singmember or rod 8. The amount and degree of intensity of such pull may, of course, be altered by appropriate change in the shape ,or the amount of inclination of the cam-edge 30, orby changing the lengths of the arms of the bellcranklever. This mechanism is found to act free 1y and without tendency to stick cramp or bind. The-requisite variat ons 1n pressure are easily imparted? to the resistor-diskcompressing member even in the latter stage of its resistance decreasing movement. t involves a minimum number of parts, is anexpensive to manufacture andis particular-' 1. The combination with asupport and a compression rheostat mounted onsaid sup and including an endwise movable operatingrod, of a non-endwise movable rockshaft journaled on said support in spaced endto-end relation with said rod, the axes .of said rod and rock-shaft being substantially parallel, and connecting mechanism for converting rocking movementsof said shaft into endwise movements of said rod.

2. The combination with a rheostat having an endwise movable operating rod, of a rock-shaft disposed in end-to-end relation with such rod, the axes of said rod and rockshaft being substantially parallel, a bellcrank-lever having one of its arms connected to said rod, an operating arm on said rockshaft, and a connection between'said operating arm and the other arm of said bellcrank-lever for swinging the latter.

3. The combination with a com ression rheostathaving an endwise movab e operating rod, of a rock-shaft disposed in endto-end relation with such rod, the axes of said rock-shaft and rod being substantially parallel, a bellcrank-lever having one of its armsconnected to said rod, and a cam and follower connection between the other arm of the bellcrank-lever and said rock-shaft.

4. The combination with a com ression rheostat having an endwise movablb operating rod, of a rock-shaft disposed beyond one end of and extending substantially in the one end of and extending substantially in the same direction as said rod, ac'am secured an endwise movable operatto the end of said rock-shaft nearer said I operating rod, a bellcrank-lever having one of its arms transverse to and connected to said rod, the other arm of said. bellcrank extending in the same general direction as said rod'and shaft and engaging said cam.

6. The combination of a base having at one end a wall at right angles to said base, with a compression rheostat'mounted on said. base-and having an operatingpulhrod parallel to said base and at right'angles to said end-wall, a rock-shaft journaled transversely of and cam' on sai rock-shaft within .saidend-wall, and a bellcrank lever fulcrumed on said base and having one of its arms in engagement with said cam, the other arm of said bell-' crank-lever-being apertured'to receive said pull-rod, and means on the end of said pullrod constituting a head against whichthe bellcrank-lever is pressed to exert a pull on "said rod. In testimony whereof, I have signed my name to this specification.

'. -DANIEL H. CHASON.

(passing through said end-wall a 

